This invention relates to a process and an arrangement for determining the position of at least one point of a vehicle moving along a given track as well as their use for determining the distance of various vehicle points. An important application of the invention relates to precise position determination and checking of the length of railway vehicles, i.e., trains.
With respect to determining the position of track-guided vehicles, e.g. railway vehicles, it is known to detect the presence of a train in a respective track section using assigned track circuits or electrical contacts in the form of electronic track contacts or axle counters. Furthermore, systems are known for influencing a train in a punctiform manner--see German patent Document DE 31 06 629 C2--and for the line-shaped influencing of a train--see European patent Document Offenlegungsschrift EP 0 593 910 A1, which can also be utilized for vehicle locating. A system of this type, with a line-type influencing of the train, in which position measuring data are obtained for determining the position by detecting track conductor cables with crossing points existing along the track, on the one hand, and by detecting the covered distance via a path-measuring wheel, on the other hand, independently of one another, is described in the journal essay by R. R. Ro.beta.berg, "Line-Type Train Influencing", Eisenbahntechnische Praxis 1967, Page 2 to 6. The obtained data are compared with one another in this system. In U.S. Patent Document U.S. Pat. No. 5,129,605, a system for determining the position of railway trains is described in which, preferably, data of a satellite-based system in the form of the so-called GPS (Global Positioning System) system are used for determining the position with the aid of special filter algorithms and compensating calculations. In intervals without GPS data, measuring data of a wheel speed indicator or of path markers placed on the side of the path are used.
In the publication by J. M. Ory, et al., "Procede non conventional de localisation d'un mobil ferroviaire--Application et realisation a la SNCF", ITTG 93, Symposium International sur L'Innovation Technologique dans le Transport Guides, Lille, France 1993, Actes S. 277, a process is described for determining the position of track-guided vehicles from a detection of the track position and of the track wear profile. The sensing system contains a special measuring car with three bogies and an extremely rigid construction. The measuring car senses the rail level as well as superelevations, peaks and variations of the rail spacing. From the respective measured rail profile, by means of a data correlation with a corresponding previously recorded desired data quantity, the position on the path is derived. However, in this case, comparatively high computing expenditures are required and the site precision is limited to approximately 10 m.
In European patent document EP 0 605 848 A1, a process is indicated for determining the position of railway trains using an inertial platform in which the vehicle location is calculated with a priori data by a recursive estimation using Kalman filtering. For promoting the position determination, path markers along the path are also required.
An arrangement for determining the location of a track-guided vehicle which uses such path markers along a travelled route is also disclosed in German patent document Offenlegungsschrift DE 32 00 811 A1.
From U.S. Patent Document U.S. Pat. No. 5,072,396, a navigation system for airplanes is known. In this navigation system, infrared aerial photos are taken of the respective flown-over area for determining the position of the airplane. The corresponding measuring data are correlated with data of a list which was prepared beforehand of the locations of characteristic objects in the landscape.
The present invention is based on the technical problem of providing a process and an arrangement of the above-mentioned type by which a precise position determination for track-guided vehicles is possible with a comparatively high error tolerance. The process and arrangement can also be used for monitoring the vehicle length, for example, for controlling the completeness of the train in the case of long railway trains.
This problem is solved by a process for determining the position of at least one point of a vehicle moving on a given track. In a mutually independent manner, at least a number n of different types of position measuring data, with n being greater than or equal to three, are obtained by detecting objects present along the track, the travelled path length, and the travelled route course. For each type of detected measuring data, a position result is determined by a respective correlation of the detected measuring data with a pertaining filed desired data quantity. The vehicle position is determined from the obtained position results by an m-out-of-n decision making process, which contains the determination of a given number m (for example, 2) from the number n of independently determined position results situated within an interval with a given resolution width. For the analysis, the concerned interval is evaluated as the position to be determined.
An arrangement is also provided to solve the problem. The arrangement determines the position of at least one point of a vehicle moving along a given track, in which, for carrying out the position determination for the at least one point of the vehicle according to the above process, the arrangement includes a computer unit for carrying out the data correlations as well as the m-out-of-n decision finding process; memories which can be read out by the computer unit and in which the desired data quantities are filed; and a sensing system for obtaining position measuring data which includes at least an object recognition sensor unit for obtaining object site data, a path length measuring unit for obtaining path length data and an angle-of-rotation measuring unit for obtaining route course data, being arranged on the vehicle side.
In the novel process, first position measuring data are obtained in at least three mutually independent manners at relatively low expenditures. The data are then, each separately, correlated with a pertaining stored desired data quantity; that is, the data are compared in the form of a so-called map-matching. This is followed by a decision making step, in which the thus obtained position results are mutually analyzed using an m-out-of-n selection process. This approach consists of determining in which position interval with a predetermined resolution width of, for example, 1 m, a given number m of the obtained number n of mutually independent position results is situated. The concerned interval is then valued as the vehicle position to be determined, in which case the other n-m position results are not taken into account. This excludes measuring errors in a simple and reliable manner, which makes the process error-tolerant and permits a position determination which is reliable with respect to the signalling technique.
In the case of this process, satellite systems and route-side devices are not absolutely necessary. On the contrary, for determining the vehicle position according to this process, it is sufficient to detect objects which are present along the route anyhow, as well as the covered path length or, as an equivalent thereto, the respective travelling speed and the course of the route. The route-side arrangement of transponders or other special path markers is optional, while the structure which normally exists is utilized for the detection of characteristic objects. For track-guided vehicles, particularly suitable objects are used as reference points for track position measuring, such as marked measuring points and overhead line masts. Other landscape-specific objects, such as masts, bridge elements, mouths of tunnels, point mechanisms, and the like, can also be used.
For implementing the process, an arrangement is suitable which requires only elements arranged on the vehicle side in the form of an appropriately designed computer unit, the required data memories, and the suitable sensors. The sensors include at least one object recognition sensor unit, one path length measuring unit and one angle-of-rotation measuring unit. An important advantage achieved as the result of this process and arrangement consists of low infrastructural expenditures for the position determination and of the fact that reasonably priced commercially available elements can be used for the configuration of a reliable, error-tolerant system. In addition, the high precision of the systems obtained at the given expenditures, if required, permits a considerable increase in the operational route capacity in the case of track-guided traffic systems. In connection with suitable communication systems, improvements can also be achieved with respect to the disposition and logistics in this traffic system.
In a preferred embodiment of the process, the detection of path markers is utilized, which are arranged on the track side, for obtaining another type of position measuring data and a further independent position result. This may be advantageous particularly for applications in which the route-side path markers already exist for different reasons. For implementing the process, an arrangement having a sensor system includes a path marker reading apparatus is particularly suitable. A pertaining desired data quantity of the path markers is filed in a path marker list memory which can be read out by the computer unit.
In the case of a use of the process, a separate position determination takes place for a forward and a rearward position of the vehicle, as the result of which, by forming the difference, the distance between these two points can be determined. On the one hand, the vehicle length can therefore be continuously monitored. This may be desirable particularly for checking the completeness of long railway trains. On the other hand, because of an evaluation of successively obtained spacing results, the position determination results can additionally be assured with respect to their reliability. For this application purpose, a particular arrangement is further developed.
For recognizing objects along a given track, particularly at least one picture camera or a picture-generating radar sensor can be disposed in the process-implementing arrangement. In each case, the camera or sensor is provided with a processing unit connected downstream.
A further preferred arrangement contains a GPS receiving part by which, for increasing the measuring precision of the system particularly when the vehicle is stopped, high-precision measurements can be carried out at support points. The data of the other position determination methods can then in each case be updated or corrected appropriately.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.